There is no doubt that jovian planets possess a complicated internal structure, as indicated by by theoretical models and Juno mission collecting data on Jupiter [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}, [9]}, [10]}, [11]}. It seems that the internal model which goes well with the current observational data must have at least 3 layers: a diffusive core build of heavier elements, a mantle mainly composed by metallic hydrogen with helium's and heavier elements' admixture. The outer layer mainly consists of molecular hydrogen with helium rain and silicate droplets [12]}. Apart from such a complex structure, there is still no consistent equation of state describing a mixture of hydrogen and helium in the pressure range approaching megabar while the temperature can reach even a few thousands kelvins [11]}, [14]}, [15]}. Despite this, we can still model a Jupiter-like planet with the use of a simplified and analytical equation of state, as presented further, because it was demonstrated that it can produce a cooling model with the nowadays' surface temperature close enough to the actual value [16]}, [17]}. Since the model is simple, it also allows us to trace differences provided by the scalar-tensor gravity with respect to the Newtonian one. Therefore, we will follow the derivation of the atmospheric, boundary, and convective interior given by [16]} and further studied by [19]}.
